change.c

/************************************************************************/
/* British currency uses the following:				        */
/* 								        */
/*  4 farthings = 1 penny;					        */
/* 12 pence     = 1 shilling;					        */
/* 20 shillings = 1 pound.					        */
/* 								        */
/* Given the above, we should be able to:			        */
/*   add and subtract currency;					        */
/*   find the cost for n items at the price indicated (multiply);       */
/*   find the cost of 1 item, given the cost of many (divide).	        */
/* 								        */
/* Results will be provided in pounds, shillings, pence, and farthings. */
/************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

#define EOLN '\n'
#define VERSION "0.2"
#define VERSION_DATE "16 November 2025"

enum OP_T { DONE, INIT, ADD, SUBTRACT, MULTIPLY, DIVIDE };

void printVersion(void) {
  printf("CHANGE Version " VERSION "\tM. Chappell\t" VERSION_DATE "\n");
  printf("Compiled: " __DATE__ "\n");
  return;
}

int getAmount(void) {
  /* Returns number of farthings */
  int accumulator=0;
  int farthings=0;
  int pence=0;
  int shillings=0;
  int pounds=0;
  int c;
  bool valid = false;

  do {
    printf("Enter amount as pounds shillings pence farthings:\n> ");
    scanf("%d %d %d %d", &pounds, &shillings, &pence, &farthings);
    if ((pounds>0)||(shillings>0)||(pence>0)||(farthings>0)) {
      valid = true;
    } else {
      printf("Currency must greater than or equal to zero!\n\n");
    }
  } while (!valid);

  while ((c=getchar())!=EOLN) ; /* Eat EOLN */

  accumulator = farthings + 4 * (pence + 12 * (shillings + 20 * pounds));

  return accumulator;
}

void printAmount(int n) {
  int farthings=0;
  int pence=0;
  int shillings=0;
  int pounds=0;

  pounds = n;
  farthings = pounds % 4;
  pounds /= 4;
  pence = pounds % 12;
  pounds /= 12;
  shillings = pounds % 20;
  pounds /= 20;

  printf("\t%d pounds, %d shillings, %d pence, %d farthings.\n",
	 pounds, shillings, pence, farthings);
  
  return;
}

void printMenu(int money) {
  printf("\n");
  printf("Your current money is:\n");
  printAmount(money);
  printf("\n");
  printf("Select from the following:\n");
  printf("\n");
  printf("\t1.\tInitialize.\n");
  printf("\t2.\tAdd currency.\n");
  printf("\t3.\tPay amount.\n");
  printf("\t4.\tMultiply by a factor.\n");
  printf("\t5.\tDivide into shares.\n");
  printf("\t0.\tQuit.\n");
  printf("\n");

  return;
}

enum OP_T getOperation(int money) {
  int c, n;
  char buffer[1024];

  printMenu(money);
  do {
    printf("Enter selection (0-5): ");
    fgets(buffer, 1024, stdin);
    n = atoi(buffer);
    printf("\n");
  } while ((n<0) || (n>5));
  
  return (enum OP_T)n;
}

int performOperation(enum OP_T op, int amt) {
  float operand;

  switch (op) {
  case INIT:
    printf("How much currency do you have?\n");
    amt = getAmount();
    printf("Your total is:\n");
    break;
  case ADD:
    printf("How much did you receive?\n");
    amt += getAmount();
    printf("Your total is:\n");
    break;
  case SUBTRACT:
    printf("What was the cost?\n");
    amt -= getAmount();
    printf("Your remaining curency is:\n");
    break;
  case MULTIPLY:
    printf("What is your multiplier?\n");
    scanf("%f", &operand);
    amt *= operand;
    printf("After multiplication your result is:\n");
    break;
  case DIVIDE:
    printf("How many times would you like to divide the amount?\n");
    scanf("%f", &operand);
    amt /= operand;
    printf("Each Share would be:\n");
    break;
  case DONE:
    printf("Your ending balance is:\n");
    break;
  } /* switch */

  return amt;
}

int main(int argc, char **argv) {
  int money = 0;
  bool done = false;
  enum OP_T op;

  printVersion();
  /* Any arguments will quit after printing the version. */
  if (argc>1) {
    return EXIT_SUCCESS;
  }
  while (!done) {
    op = getOperation(money);
    money = performOperation(op, money);
    printAmount(money);
    if (op == DONE) {
      done = true;
    }
  }

  return EXIT_SUCCESS;
}
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Wednesday, 12 August 2026 Michael J. Chappell Contact me at: mcsuper5@freeshell.org
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